This invention relates to heaters of a type that are retained in a threaded bore passing through the wall of the engine block. Such heaters include a threaded nipple, an outwardly facing end portion having a diametric dimension greater than that of the nipple, and a sharp shoulder connecting the nipple and end portion. In the prior art, a washer is disposed on the nipple for compression between the shoulder and the wall of the engine block surrounding the bore. The washer provides a sealing function to prevent the escape of engine coolant from the block, and a damping function, to reduce the transmission of vibration between the engine block and the block heater which tends to loosen the seal across the interface.
The reliance upon a sealing washer is generally found to increase the installation time of the block heaters. In addition, the inadvertent loss of the sealing washer in the installation process can engender considerably increased costs to rectify the deficiency when it becomes apparent. Although it is well known to capture washers on screwed members, this tends to increase assembly costs of small assembly run items such as block heaters.
It is an object of my invention to provide washerless block heaters for automotive engines.
It is another object of my invention to provide block heaters for automotive engines that are more easily assembled into the automotive engine, with reduced margins for error.